An area extending 19 miles (31 km) in all directions from the plant is known as the "zone of alienation." It is largely uninhabited, except for a few residents who have refused to leave. The area has largely reverted to forest. Even today, radiation levels are so high that the workers responsible for rebuilding the sarcophagus are only allowed to work five hours a day for one month before taking 15 days of rest. Ukrainian officials estimate the area will not be safe for human life again for another 20,000 years.